Chamber is used to study atmospheric turbulence effects on FSO signals and this experiment is done inside the laboratory to avoid the interference of sunlight light and also it is hard to create turbulence outside laboratory as outside temperature and pressure will affect the turbulence created inside this chamber. This project is all about controlling all parameters (temperature, pressure, humidity) using sensors, fans, thermistors through embedded circuit.
As observed from previous work, high end microPIC (PIC18 series) although it has many functionality and large program memory size, it is hard to control all sensors, fans, thermistor using 1 PIC1866K80, So in this project mid-range PIC (PIC16 series) are used to control sensors, fans and thermistors.
In this project, temperature, humidity, pressure sensors are controlled by different microcontrollers and taking their reading to manage the performance of PWM fans and thermistors inside the chamber. These components are very important to configure and monitor the atmospheric condition inside the chamber.
This project focuses on the use of PIC16 family microcontrollers to be programmed in C language or in assembly to control all sensors, fans and thermistor and build PCB layout.
In this project, Rs-232 or Com port will be used as an interface to control the PIC16 microcontroller instruction and procedure through computer.
Table of Contents
Introduction
Previous Work
Motivation
Literature review
Free Space Optical Communication
Advantages and Disadvantages of FSO
FSO System
Effects of Atmospheric Attenuation of FSO Communication
Performances of FSO Links
Aim and Objectives
1. Programming microPIC for temperature measurement
2. Programming microPIC for humidity measurement
3. Programming microPIC for pressure measurement
4. Programming microPIC for controlling PWM fan
5. Programming microPIC for controlling Thermistors
Temperature Sensors
Working of DS18B20 temperature sensor
Power supply for DS18B20
Memory of DS18B20
DS18B20 Sequence
Coding for PIC16F627A and DS18B20 in C language
Arduino Program for more than 1 DS18B20 temperature sensors
PCB and schematic diagram
Humidity Sensor
Working of SHT11
Communicating with SHT11 humidity sensor
Calculating relative humidity
Coding for PIC16F627A and SHT11 humidity sensor
Arduino Program for SHT11 sensor
PCB and schematic diagram for SHT11
Pressure Sensor
Working of MPX4115a pressure sensor
Calculating pressure
Coding for PIC16F627A and MPX4115a pressure sensor
Arduino Code for MPX4115a
PCB and Schematic Diagram for MPX4115a pressure sensor
Results and Discussion
Conclusion and Further Work
Project Goals and Scope
The primary aim of this project is to develop an embedded control system for an indoor atmospheric chamber designed to simulate environmental conditions for Free Space Optical (FSO) communication testing. The project focuses on the accurate regulation of atmospheric parameters, specifically temperature, pressure, and humidity, using dedicated sensors and microcontroller-based circuitry to manage PWM-controlled fans and thermistors.
- Implementation of microPIC (PIC16 series) control systems for environmental parameter monitoring.
- Integration of specialized sensors (DS18B20 for temperature, SHT11 for humidity, and MPX4115a for pressure).
- Development of PCB layouts and C/assembly language programming for sensor data acquisition and control.
- Interface development between microcontrollers and computing systems via RS-232/COM ports for real-time monitoring.
Excerpt from the Book
Free Space Optical Communication
Free space optical communication (FSO) is an optical communication technology which transmits data for telecommunications or computer networking by propagating light in form of laser using lenses and mirrors to focus and redirect the beam through free space (e.g. Air, outer space, vacuum).[31]
Other name for FSO communication is Wireless Optical communication (WOC), fibreless or Laser Communication .Nowadays, it has witness a vast development and is categorised among as one of the different types of wireless communication. At clear atmospheric conditions, it provides a wide service and requires point-to-point connection between transmitter and receiver FSO is basically the same as fiber optic transmission. The difference is that the laser beam is collimated and sent through atmosphere from the transmitter, rather than guided through optical fiber [2]. The FSO technique uses modulated laser beam to transfer carrying data from a transmitter to a receiver. FSO is affected by attenuation of the atmosphere due to the instable weather conditions. Since the atmosphere channel, through which light propagates is not ideal.[28] [29]
FSO systems are sensitive to bad weather conditions such as fog, haze, dust, rain and turbulence. All of these conditions act to attenuate light and could block the light path in the atmosphere. As a result of these challenges, we have to study weather conditions in detail before installing FSO systems. This is to reduce effects of the atmosphere also to ensure that the transmitted power is sufficient and minimal losses during bad weather.
Summary of Chapters
Introduction: Outlines the research context at Northumbria University regarding FSO systems and the need for an upgraded indoor chamber to replicate environmental variables.
Literature review: Provides a theoretical foundation for FSO technology, discussing its operating principles, sensitivity to atmospheric conditions, and associated performance metrics.
Aim and Objectives: Defines the specific goals of controlling temperature, humidity, and pressure within the chamber using microPIC microcontrollers.
Temperature Sensors: Details the operational and programming requirements for the DS18B20 digital temperature sensor, including hardware implementation and communication protocols.
Humidity Sensor: Explains the interface requirements, command structures, and mathematical formulas for calculating relative humidity using the SHT11 sensor.
Pressure Sensor: Covers the functional characteristics of the MPX4115a analogue pressure sensor and its integration into the control system.
Results and Discussion: Analyzes the experimental progress, highlighting the transition to Arduino for successful data acquisition when challenges with microPIC implementation arose.
Conclusion and Further Work: Summarizes the project outcomes and provides a critical evaluation of the implementation difficulties encountered with the intended microPIC approach.
Keywords
Free Space Optical Communication, Atmospheric Turbulence, microPIC, PIC16, DS18B20, SHT11, MPX4115a, Humidity Sensor, Pressure Sensor, PWM Control, Embedded System, PCB Design, Wireless Communication, Data Acquisition, Microcontroller Programming.
Frequently Asked Questions
What is the core focus of this project?
The project focuses on creating a controlled environment within an indoor chamber to simulate atmospheric turbulence, which is critical for evaluating Free Space Optical (FSO) communication links.
Which microcontrollers are utilized in this work?
The project initially targets the PIC16 series microcontrollers, though Arduino platforms were subsequently utilized to achieve functional sensor data collection.
What is the primary objective regarding environmental control?
The goal is to precisely monitor and control ambient temperature, pressure, and humidity to accurately replicate real-world weather conditions such as fog and turbulence.
What scientific methodology is employed?
The methodology involves researching sensor data sheets, designing PCB layouts for sensor interfacing, implementing firmware in C/Assembly for data acquisition, and utilizing serial communication for system monitoring.
What components are covered in the technical chapters?
The book details the technical integration of DS18B20 temperature sensors, SHT11 humidity sensors, and MPX4115a pressure sensors, along with associated PCB schematics.
How is the performance of the communication system measured?
The work discusses performance parameters for FSO links, including Bit Error Ratio (BER), received power, and the impact of atmospheric attenuation.
Why was the transition from microPIC to Arduino necessary?
The author encountered communication challenges between the intended PIC microcontrollers and the sensors, necessitating a shift to the Arduino platform to successfully obtain valid measurements.
What are the specific temperature sensors used in the research?
The project utilizes the DS18B20, which is a one-wire bus digital temperature sensor capable of user-configurable resolution.
How is the atmospheric pressure calculated in the project?
Pressure is determined using the MPX4115a sensor, with calculations based on a transfer function that accounts for voltage output and temperature-based pressure errors.
What does the final report conclude about the project's progress?
The conclusion notes that while PCB designs were completed, programming for certain elements like fans and thermistors remained incomplete due to time constraints and technical hurdles during the microPIC implementation phase.
- Arbeit zitieren
- Ninad Gondhalekar (Autor:in), 2013, Controlling the atmospheric turbulence, microPIC programming, München, GRIN Verlag, https://www.hausarbeiten.de/document/284209
